This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Using a rhesus monkey model, this project is designed to provide a better understanding of how psychosocial stress, imposed by social subordination, affects brain maturation and emotional development in females and whether this is influenced by polymorphisms in the gene that encodes the serotonin re-uptake transporter (5HTT), a protein essential for normal serotonin neurotransmission and emotionality. Significant progress was made during the current year on the first cohort of adolescents (n = 37) that are housed in large social groups at the Field Station. Data show that adolescent females are less sensitive to glucocorticoid negative, suggesting they may be particularly vulnerable to the stress of social subordination. Furthermore, subordinate adolescent females with the s-variant polymorphism in the gene encoding the 5HTT are more reactive to novel objects, reflecting greater emotional reactivity. Structural MR, DTI, and PET imaging of 5HTT and 5HT 1A receptor binding density were completed on this cohort and analyses are still in progress. As expected, the more socially dominant females of this cohort have entered puberty whereas the subordinate females have not. The second cohort (n = 39) was recruited this year and they too are housed in the large social groups at the Field Station. This group, however, is being treated with Lupron, to experimentally delay puberty and developmental increases in estradiol. Behavioral testing, glucocorticoid assessments, and neuroimaging have begun on this cohort. These studies will show the importance of estradiol for behavioral and brain maturation during adolescence in females.